Aha! I did a bunch of searching in the FMS Forum
and found references to two good tutorials (in case other people want to see them).
All comments about texture maps refer to square ones, usually 256x256 or 512x512. Yours is 1600x1200. I moved some sections of image around and resized down to 512x512 overall. Textures then showed up in FMS! Of course they need repositioning since they get moved in the bmp file.